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Human power is the rate of work or energy that is produced from the human body. It can also refer to the power (rate of work per time) of a human. Power comes primarily from muscles , but body heat is also used to do work like warming shelters , food, or other humans.
As in other mammals, human thermoregulation is an important aspect of homeostasis. In thermoregulation, body heat is generated mostly in the deep organs, especially the liver, brain, and heart, and in contraction of skeletal muscles. [1] Humans have been able to adapt to a great diversity of climates, including hot humid and hot arid.
Origins of heat and cold adaptations can be explained by climatic adaptation. [16] [17] Ambient air temperature affects how much energy investment the human body must make. The temperature that requires the least amount of energy investment is 21 °C (70 °F). [5] [disputed – discuss] The body controls its temperature through the hypothalamus.
For an overall efficiency of 20%, one watt of mechanical power is equivalent to 18 kJ/h (4.3 kcal/h). For example, a manufacturer of rowing equipment shows calories released from "burning" food as four times the actual mechanical work, plus 1,300 kJ (300 kcal) per hour, [16] which amounts to about 20% efficiency at 250 watts of mechanical output.
Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
Energy intake is measured by the amount of calories consumed from food and fluids. [1] Energy intake is modulated by hunger, which is primarily regulated by the hypothalamus, [1] and choice, which is determined by the sets of brain structures that are responsible for stimulus control (i.e., operant conditioning and classical conditioning) and cognitive control of eating behavior.
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The resting human body generates about two-thirds of its heat through metabolism in internal organs in the thorax and abdomen, as well as in the brain. The brain generates about 16% of the total heat produced by the body. [8] Heat loss is a major threat to smaller creatures, as they have a larger ratio of surface area to volume.